


Seven at Sea, Seven at Land

by Fyliwion



Category: Sherlock (TV), Sherlock Holmes & Related Fandoms
Genre: Alternate Universe, Fairy Tale Retellings, Falling In Love, Fantasy AU, First Kiss, Gen, Gift Exchange, Implied/Referenced Drug Use, Johnlock Roulette, M/M, Mycroft is an arse, Sherlock wants to be a mortal, This is not the Little Mermaid, exchangelock, mer!lock, merman
Language: English
Status: Completed
Published: 2014-12-31
Updated: 2014-12-31
Packaged: 2018-03-04 13:37:27
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 8,863
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/3070199
Author URL: https://archiveofourown.org/users/Fyliwion/pseuds/Fyliwion
Summary: <blockquote class="userstuff">
              <p>Sherlock had watched their ships from year to year, and wanted nothing more than a chance to become a mortal. Mortal’s with their tricks and trades, their cities and their art. Seven years he would be given the chance, but the price of staying longer was one that he would never hope to attain.</p>
            </blockquote>





	Seven at Sea, Seven at Land

**Author's Note:**

  * For [RainyDays_and_DayDreams](https://archiveofourown.org/users/RainyDays_and_DayDreams/gifts).



> _**Prompt:** How about something with mer!lock? Maybe one of them is a human, and the other is a merman... They meet when they're older, and the merman takes the human to explore their world, and the human takes the merman to explore his (though that's not necessary)... Idk, I just like mer!lock. But if that's too much, something that involves SciFi, maybe steampunk or cyberpunk, will do? _
> 
> (In fairness... I nearly did Steampunk since that's much more my area. That said... I had a suspicion it would simply turn into Canon!Fic with dirigibles and so this emerged instead).
> 
> Thank you to my lovely beta **Eialyne** who put up with my bugging her just as she gets back from vacation.

It was rare that Sherlock stood so still, gazing past the roaring waves like an incandescent statue overlooking the cliff.

His hand clenched as his eyes flickering to the water and past the setting sun. A pale light glistened in a look of want so striking that for a moment John worried Sherlock might dive over the side and into the waters tumbling below.

Instead, the man's colour fled from his face, and his long eyelashes fluttered shut to block out the image visible in the sea's depths. There was a momentary question, and then he turned around and walked away from the abyss.

John's heart was pounding as he watched the other man. It was a profounding effect, that held no bearing in his own thoughts. Something about the way the ocean wind picked up around the man, and how the waves seemed to lift up and try to reach the detective as he walked down the cliff. Suddenly came a fluidity to the detective's movements, like the water had lent some of its grace to his steps.

With the setting sun casting its rays, John contemplated what strange dream he had slipped into.

Except--

The wind picked up, and the chill sunk into his bones. He could hear the call of the gulls going to hunt in the open waters, and the shadows began to set in for the night.

"Sherlock wait up!"

By the time he fell back into step with him, the expression on Sherlock's face nearly had him pull back. It was like nothing he'd seen prior. Nothing that he had any familiarity with in the years that he had run with the other man.

It was not quite like the fear at Baskerville, nor the glimpse of loss during John's wedding. Nor did it hold the egotism that was evident in his actions when it came to matters such as stealing from the morgue, or a new experiment that John would never let on the kitchen table.

This was an unknown plane.

As unperceivable as the first time they met at Bart's years before.

He didn't speak, he didn't even look down although his steps slowed to match the other mans. They went back to their loaned cottage without another word, the crash of waves chasing behind them.

* * *

 

_"We have an agreement."_

_"Decidedly unfair given the duration of your own stay Mycroft. Seven years a land, seven to sea? Why should I be so confined when no one else finds themselves trapped to such ridiculous rules?"_

_"Most never have the opportunity for more than a day or so. Were you able to prove less reckless, or capable of some semblance of common sense I might reconsider. That said, you should be thankful I am allowing you any margin of such action at all."_

_"Seven years is not enough time to fully flesh out a human life Mycroft. Seven years is hardly enough time for anything!"_

_"Seven. Or I shall see to it you never step on land at all."_

_There had to be otherways. He knew there were stories of their folk captured, held, or disappearing onto land to never return to their realm. Mycroft managed to stay above more than he visited below, but then he was their liaison between the two worlds._

_Spy was the more accurate word._

_"I'll find a way to stay," he said sniffing. "Something even you cannot fight against."_

_A laugh from his brother, harsh and condescending that left a chill down his arms. "Love, baby brother? Ah yes, I suppose you could obtain a soul for yourself and become truly human until you forsake the sea entirely. But then you can't find it in yourself to love yourself, how could you ever obtain a soul?"_

_"It's a possibility."_

_"Emotions are a weakness Sherlock. Messy things that lead to nothing but inevitable sorrow. I should rather see you dead, than scattered as sea-foam upon the waves."_

_It was unlikely, and Sherlock himself abhorred the idea. He would find another way, or perhaps talk Mycroft into another year or two- or prove himself so necessary there was no way he could refuse him._

_His brother was right._

_Love? He would never find a soul._

 

* * *

 

He hadn't seen Sherlock sleep since they arrived.

That wasn't to say the man didn't. There was the possibility he had an hour or two when John was out, but from what John had divined it seemed unlikely.

Every morning the detective's features grew more wane . The salt air made his hair less curls and more an unruly mess. His skin became pallid and ghostly with dark circles beneath his eyes that grew more defined each passing day.

They were suppose to be on a holiday, while they finished up the last pieces of a fairly involved case Sherlock had begun the week prior. That said, the salt air seemed an anathema to the detective rather than any type of restorative.

"Come out for a swim Sherlock," John said one morning, with towel over his shoulder and dressed for the water. It was still a tad cool, but he planned to take advantage of every second they were needed to remain.

"No."

It sliced through the air like a knife, as blistering as if he'd given a deduction Anderson might have offered up. John felt a stab at the response, and his brow furrowed in disconcernation.

"What?"

"Must you have me repeat myself? No. Freeze if you like, but I shall remain here," his eyes flickered towards the window where the water could be seen from a distance. The white waves rollicked as the sun glinted welcomingly over their tops.

"It's not that cold Sherlock," John caught the look of disdain on Sherlock's face and sighed, "At least come out and sit on the beach if you're so against it then. It'll do you some good to get a bit of sun."

Sherlock sniffed with a glare decorating his face as though John had committed some atrocity that could only be matched by offering a form of death.

"Go. I have a case to consider unless you forgot."

John hadn't, but they had been on a standstill for the past two days. Sherlock may have solved it, but they lacked the proof and the details necessary to arrest, which meant they still needed the final contender talked. Until then...

He rolled his eyes and turned for the door, "If you change your mind feel free to . Wouldn't hurt for you to get a bit of sun though."

"Cancer John. I already have one vice, I hardly need another."

* * *

 

_A soul._

_Everything he'd read, studied, and found in the past several months told him there was little hope of staying without it._

_Mortality was fascinating. People might be akin to goldfish, small and idiotic, but compelling at times when they sought to be. Their cities were beyond anything he had seen, and they held an enchantment that kept his mind entertained for hours._

_But seven years. There were other traditions that said the same- seven years at sea, seven on land. Always a time limit without a dispensation that allowed the laws to be thwarted._

_To fall in love?_

_The easiest method, one that appeared tried and true from what he'd managed to gather. But Sherlock had not found the slightest inclination to find selflessness in these humans._

_His experiments at taking them to bed thus far had been... interesting. But the emotions were fast and fleeting, and he'd grown bored just as quickly as they had held his interest._

_Women had never held any particular inkling for him, and men were good for a moment, but beyond his keen._

_Yet, there were other books. More difficult to procure and most no longer used by the scientific and unimaginative mortals of these days. Alchemy, science, all a craft in one where mortals were obsessed with changing lead to gold and creating men._

_But Sherlock sought to find something else entirely._

* * *

 

John woke up with a start with no hopes of returning to his earlier slumber. The room was dark excluding the faint hint of moonlight that poured through his window. He laid in the faint light listening to the sound of waves battering across the sand.

There was no sound within the cottage implying the detective had succomb to sleep at last or fallen into his mind palace for the rest of the night. John gave in, dressing quietly and padded through the hallways careful not to wake him should it be the first.

A faint light was on in the kitchen with another on in the sitting room, yet there was no sign of the other man. In bed then, John decided, which left him to his own disconcerting thoughts from his dream.

The waves continued their crashing outside, and John moved to the window that overlooked the ocean. A terrible idea, but the waters were inviting under the pale face of the moon. The warm summer air blanketed him, and the water would clear his head. Without a second thought he fetched a towel and made out into the night.

The beach was rocky, but the waves were calmer than they had earlier in the day. The tide was in, and the water lapped at his feet as he moved past the shore.

Inarguably dangerous, but John was a strong swimmer and the danger simply added a greater thrill to the night. He had loved trips out to the lochs and ocean when he was a child. When he had looked to enlist initially he had thought to join the Navy, but there was more work to be had in the Army for a doctor, but little swimming to be had when you were at war in a desert.

He lay on his back chuckling as he stared up at the stars, visible for miles in the open water. Cassiopeia and Andromeda staring back at him, swirls of the Milky Way and even mars, barely touching the horizon and brilliantly red.

How odd. For a man who once wished to be a pirate to delete the universe and hate swimming.

John was nearly a kilometre out when he felt something slip against his leg.

He froze, his mouth went dry, and his paddling ceasing. Another soft brush of something and he felt his eyes shut. Perhaps a large fish was all. Sharks were rare, and... no there was a sharpness. They did not have scales.

He felt the current pass him, and he began to think it had swam back to sea when the water breached little more than two metres away.

Years of military training kept him from being startled, but it was a close thing. He swam back further and then nearly slipped beneath the waves at what he saw.

Moonlight, glinting off scales. A tail fin that was nearly the span of his body, and a long tail that was serpentine and dove in the waters. The length? Six... perhaps seven metres at least. A deep vibrant blue, incandescent under the moonlight that was twisted with silver starlit veins through the colours, and nearly black once in the shadows. It was nothing he had ever seen- mesmerizing and fantastical.

He stared, caught up with the beauty, and so entranced that he nearly failed to recognize the human torso for what it was a moment later.

Muscular, pale, and water beading on the skin as though it were waterproofed. Hair hung nearly shoulder length, curling at the ends and thick and black. A man, no doubt, the torso built and lacking breasts, but carefully structured from years of swimming- arms that were taut and abdomen carefully sculptured.

Sharp cheekbones that were unquestionably recognizable.

A bullet wound just below the right ventricle just along the rib cage. John might have missed it entirely if the light hadn’t hit his body at precisely the right moment.

"Dear God."

The man's head turned. Blue eyes, wild and unreadable, met John’s wide with horror. A bit of a mad laughter poured from John's lips when he saw what appeared to be small gills just under the earlobes.

Sherlock let out a cry and dove back beneath the waves.

Stupid, stupid, stupid.

Sherlock should never have run the risk, but the call was endless and beckoning and better to give it a bit of a respite than listen to the ceaseless banter that was her cry.

A quick dip, a moment to let himself expand and connect with the waters and that should have been enough. How long it had been- though not as long as the years before. There had been some good in his forced escape by Moriarty.

There had been months gained in his time on land, although the time remaining was mere days now, and he suspected a few hours in her caress would not subdue the sea this time.

Like any other addiction, the first hit would simply make it worse in the hours to come. But he would take any moment he could to extend his stay.

If he locked himself in a room? In prison? Would he lose his legs and be left to die on dry land? Or rather, would he push himself through regardless, a rabid thing whose only goal was to find salt water and sink into her depths?

Tonight's decision had proven erroneous. He had expected John to sleep through the night, would never have considered he'd take a midnight swim quite so far out into the water. Reckless as John was, the ocean was usually good at keeping her own safe.

Yet there had been disbelief in his eyes, a look of question and Sherlock considered for a moment his options.

To tell him the truth. To give him everything. To spell out what end would come, and that if they were to ever see one another again it would be as a creature of the ocean- trapped beneath the waves and far from the cities and wonders humans had built.

For a moment he would have

He swerved, slipping beneath the waters and grabbing John's legs. Like this he was stronger, faster, and John too startled to see him coming. He twisted around, and his hand catching a stone from the bottom as they reached it, John fighting in his hands. Sherlock fought back and hit him hard against the temple, waiting as the man went limp before pulling him back to the surface.

He pumped the water from his throat and lungs and swam towards shore, the edge approaching seconds later. He slipped to the beach laying out the man and looking at his figure that the waves lapped at jealously.

Sea foam.

Perhaps it was the better option. There was some truth in the silly human stories of their sea girl so infatuated with her human prince. Once Sherlock would have had no qualms of striking a knife through the heart of John's lover to keep his legs, but now…

How ironic the act of love did not provide the mortality and soul that he so needed. He may have discovered the secret to it, may have found the emotions, but without it returned he may as well wish for wings.

The rock had left no mark. He pressed a kiss to John's temple before sliding out his tail from the water and waiting for the scales to dry and shift back to the smooth human skein.

The gills began to retract, his fingers lost their webs and the nails resuming their dull human lengths.

Human again, at least skin deep.

It would take a minute, as he fought to stand and force his legs to work. Another truth- the endless ache that always remained and had come to grow as the time lengthened on.

He forced them to stabilize, before reaching down to pick up the man. He had a sleeping pill, carefully powdered it would knock him out until late morning at least and might give him time.

* * *

_The sides of the ships glistened with the spray, white sails open and bright under the weight of the wind. Beautiful vessels, with intricate carvings of their people that, while not entirely accurate and so frequently women, were a fantasy not unlike Sherlock's own._

_"What if you are seen?" Victor had come to rest half in and half out of the water, his eyes following to the ships that Sherlock had been watching._

_"They'd never believe it," he said shaking his head. "Mirage, fantastical, some made up hallucination never to be considered."_

_He shook his eye watching as a man flew off the side of the deck and into the water. There was laughter, audible even from the distance, and the man bobbed above the edge splashing up at the deck before a second joined him._

_"You still wish to be mortal?"_

_"A pirate" he corrected. "Mortality might be interesting, but the pirates seem the most fascinating._

_They have their own ships, and keep one foot in the ocean and the other on land. No rules but those they make, and I've heard the songs relaying their deeds. How fascinating it must be." He rolled on the rock letting the sun settle over him; basking in the light with the sound of the humans not far off._

_"Pirate," Victor's voice was dry._

_"It's better than what we have now" he said shortly. "Swimming all day, sitting through dull meetings. Why even a shark is more fascinating than the absurdity than our daily duties."_

_Victor laughed, "And you live in Atlantis."_

_"Precisely. I have no interest in monitoring the currents or expanding our territory. The humans are reaching further and deeper into the ocean, and their own territories are expanding twice as quickly as ours. Unlike the lack of evolution our people have faced, the humans are constantly finding new interests and technology. It's fascinating Victor."_

_The other merman laughed, "If you say so Sherlock. It all looks like madness to me, blood thirsty and so caught up in the moment they barely see the time as it passes them by. Rash."_

_Sherlock grinned, "Rash? No Victor. Fascinating."_

* * *

"On the beach."

John couldn't remember what had occurred precisely but he knew there was something he was missing.

His dreams were interesting enough at least. Sherlock had been a merman, and he'd stumbled upon him during the late night swim.

According to the detective, he had been out swimming and something proceeded to knock him out. When he awoke and realized John had slipped off without returning he'd gone in pursuit of the man. He'd proceeded to find John passed out on the beach, miraculously not drowned, and brought him back to the land of the living.

All very auspicious and there was something Sherlock was not saying.

"Indeed. You looked rather peaceful, although the gulls seemed rather ravenous, and I thought you'd rather not face the predicament of being pecked to death."

"No. That does seem to be the most unpleasant option."

But if what Sherlock said was true he should have drowned. The tide was ravenous the night before, and John knew enough that he should have been pulled to sea, not left on the shore without so much as a tan.

* * *

 

_Mycroft found him curled a squatter's warehouse out in the East End._

_He said nothing, lifting up the too thin body and carrying him out to the car where he told his driver shortly "Tilbury Docks."_

_He combed the matted black curls, watching his brother's face as he slumbered uncomfortably. If he was a mortal he would already be dead. Mycroft's fingers strolled to the arm, turning it over to reveal the blown veins and new pinpricks from hours before._

_A wasted opportunity. He hadn't expected his brother to find something as absurd as love._

_Emotions were a hindrance, and a soul would be nothing but a burden. He'd hoped his brother might learn that- return to the sea- and then Mycroft could allow him to return occasionally as he saw fit._

_It would likely be a good premise for his ever bumbling brother._

_He had not expected this extreme._

_Sherlock's breath was shallow, barely breathing, and Mycroft lowered his head to press a kiss atop the curls, letting just a drop of life slip through him and keep his brother's pulse going as the driver sped on._

_Once they arrived they parked a ways away. Mycroft lifted up his brother, refusing his driver's assistance, and carried him to the edge of the beach._

_It was some difficulty he removed his brother's clothing. He was still trapped in whatever fever dreams the overdose had thrust upon him. Drugs did odd things to their systems, even in their human skin. Antibiotics, pain blockers, Mycroft was constantly monitoring what he was given and careful not to take anything that was not utterly meaningful._

_Once the clothes were removed he lowered him on the sand before moving back as the water lapped at the man. The saltwater playing at his feet, legs, hands, before a wave came to cover him and left in his wake a glittering tail._

_Sherlock gasped, screamed in pain as his gills returned to their rightful place and tore from his neck. There were ways to make the change easier, but Sherlock did not deserve them at that moment._

_Another scream as he turned and vomited onto the shore, Mycroft watching as nothing came up as his brother retched into the sand. His arms shook as his body worked at ridding itself of the foreign substance._

_Racking sobs of anger as he shook and looked up, meeting Mycroft's eyes with fury "What. Have. You. Done."_

_"You've done it to yourself," Mycroft said shortly. "I cannot risk our people for the sake of your habit."_

_Sherlock shook, the waves coming quicker and surrounding him as his tail thrashed in anger. His fist dug into the sand, "Seven years!"_

_Mycroft's lips pursed as he looked at him, "You may yet have your seven years, but first you must prove to me you will do something other than kill yourself with such damnable drugs. I cannot have a misstep whilst you are too indisposed to be aware of the consequences."_

_"Misstep?"_

_He sighed leaning on his umbrella with a long look to his brother, "You are of course aware of the consequences were mortals to realize our kind exist? that would happen if they truly began searching? It must not have slipped your notice during your time here Sherlock."_

_He glared, "I would never-"_

_Mycroft lifted his hand and droplets of water gathered in his palm drawing itself into a globe. In the center of the liquid a faint image of Sherlock laying in the arms of a dark haired young man came to light, "--Mmm? S'boring. The ocean. Dull.... thousands of miles down and nothing interesting. Humans...whilst idiotic are hardly as mind-numbingly boring as.... fish."_

_In the globe the dark haired man next to Sherlock stroked his shoulder, "Humans? And what does that make you Holmes?"_

_The image of Sherlock flashed a grin, pupil's blown and obviously high as a kite as he rolled on top of him, "A god."_

* * *

"You can't tell me you don't like the sea. You've been staring at it every day we've been here."

Sherlock barely heard John's chattering as he stared out at the rumbling waters. It was growing stronger and was becoming unbearable at night. He had perhaps a day left, hours really, and soon even cuffing him to the bed would not keep him from tearing after the dark waters.

Damn. Damn. Damn.

But the sound of the man's voice was a warmth that encircled him, a balm against the ripping pain that had begun shredding apart the borrowed skin and threatening to return him at any moment.

Two.... three years back he might have been willing to return. But now?

"Sherlock? Sherlock are you.... you aren't listening to a word I'm saying are you?"

He half wondered if he'd fall to the waters only to find himself spread apart into sea foam.

Sea foam might be the lesser of the two.

"Course you aren't. Why would you bother listening to me? You're the man who talks to me when I'm not even here, so why should I expect you to listen when I'm actually in the same room as you."

He should cut the ties now. Try to rip out the part of him that had turned John into a part of himself. What good were such emotions if they were not returned? He would be trapped in the ocean and this time with half a soul that belonged with neither humans nor the Mer.

"Fine. Fine. If you're going to be like that- I'll be out at the beach. Enjoying our holiday. In the water. On the beach," he said rolling his eyes and stepping towards the door.

"You repeated ‘on the beach.’ Unnecessary. It was obviously your location as you said from your initial comment."

John groaned and let the door slam behind him.

Yes. That would be best.

* * *

_"It's a job."_

_"Is it? I thought it was a hobby that was filling your time so I was not forced to listen to your unending cries of boredom."_

_Mycroft sat behind the desk at the Diogenes without even looking up. His pen darted across the paper and his mouth set in a tight line._

_"And I'm assisting people. Solving things. You can't disagree that the work is far more stimulating and useful than anything I was doing at home. They may be little more than goldfish, but sometimes the puzzles can rise which keeps my attention. Furthermore, it provides an insight for them that's unquestionable. Mycroft, you must let me stay."_

_"Seven years Sherlock."_

_Sherlock slammed his fist against the desk, "And what of you! You haven't a soul. You sit and spy on the mortals without repercussions. What year is this? Ten? Fifteen? How long before on your last trip? You cannot tell me there isn't a way if you were to deign such an agreement."_

_Mycroft sighed and finally looked up wearily. "Many years Sherlock. Many years I spent debating the ups and downs of such an action and the possibilities. I had various trips prior to being allowed such an exception. Seven years-- and you will return to the water for seven more._

_After that allowance we can discuss your return."_

_"To what? Swim about like some useless entity? Hiding from the sun and the ever deepening mortals? To go about mindlessly with our stringent rules, and worse traditions? Mycroft do not ask this of me."_

_The man's eyes glinted and he shook his head, "Five more years brother. I would not waste them were I you."_

* * *

 

He awoke to find himself standing on the edge of the water.

He was wrapped in nothing but his sheet, which he supposed was better than being entirely nude. He could feel the chill of the water and the sand was damp, but not wet enough to cause the shift. Not yet even though his skin was on fire and it felt as though he was about to be split in two.

Paralysis took over. His feet buried in the sand and his pulse in time with the pattern of the waves. He'd walked to the shore in his sleep- the call pulling his body from the bed and carrying him where the mind fought from going.

He shut his eyes. The sting of salt remaining, cutting in under his eyelids as he listened the waves and felt the cool air brush against him.

He was going to lose.

His mind may have categorized and practiced to ensure that he had no connection to the waters. His heart may have filled with ridiculous mortal notions that made him more than half human. But his body betrayed him, his body let it be known that he could hold out at most one more day- perhaps two if he was careful in his actions.

He forced one step back, enough there was no chance for the waves to rise and meet him. His legs slipped from under him and he sat upon the sand, curled in his sheet, and watched the waves come closer.

"Sherlock what are you doing?"

The detective's head swerved an hour later to see John standing behind him with a rather amused expression, "I spend the better part of week trying to get you down here, and you've bloody well dragged the whole sheet set with you. How long have you been out here?"

Sherlock tugged the blanket more warmly around him, "I needed to think."

"Naked? Before noon?"

"It's a private beach John. We are unlikely to see anyone. For that matter you haven't the entire time we've been here, or else you would have been less intent on having me join you."

John set his towel onto the sand and sat beside the man looking at the waves. "Something's bothering you."

"How astute."

"Sherlock."

The waves lapped playfully at him, and his ears were attuned to the sound of the wind picking up over the water. The cry of the gull was in his ear telling him to return, swim away, go now before the fragile peace he'd begun to make was gone forever.

"It is of no regard."

He could feel John's eyes piercing the back of his head, brushing over the salt in his tangled curls and the slight hint of brown his neck was turning in the sun. A burnished silver would be more of his shade when it was done, not quite a tan but nothing like the pallid tones London left him with.

He nearly jumped as he felt the man's fingers rest on his shoulder and brush down his arm,

"Sherlock I want to help. God, I know, better than anyone that you hate letting anyone in, but something's been bothering you this entire trip."

Molly had once mentioned the look Sherlock had when no one was looking. A look that said they would lose him- it was the same look on the airfield, the same look before Moriarty ensured he might never see him again.

John's voice stuttered, "I can't lose you again Sherlock."

The wind almost snatched it away, the cry of the gulls nearly drowning it out so it was inaudible.

The skin prickled along the arm with John's hand on it, and for the first time, Sherlock wished he had the tears to cry.

* * *

 

_The melody hung over them, glancing off the waters and keeping the few mortals left awake in fear of the shadows._

_He sat on the rock, the fiddle under his chin and the bow slipping along the strings. Rare, rare they were the opportunities on the old sea washed instrument. It had taken months to find it, longer to repair it to a point it could be played. Nothing like the one he had tucked away at home but it would do._

_Mycroft would mock him for not simply raising his voice._

_His parents would warn him away from such an open act._

_But if he could no longer have his legs? He would have this at least._

 

* * *

 

Two glasses sat upon the table, brandy in both with a crystal decanter.

Sherlock eyed them as John poured the brandy into one and held it up to Sherlock. "We've only two days left. We may as well enjoy the evening."

The brandy flowed. A good vintage, something John had been saving and brought along for the trip just in case. The morning before had boded poorly and now he would enjoy the present.

The first and then a second and a third- so rarely were they able to truly let loose and even as Sherlock complained, his own mood was dark enough that he would take what he could of his final moments.

Especially if spent with John.

He let the man pour, and when they'd finished the decanter he retrieved the rest of the bottle.

John laughed proclaiming Mycroft would likely hang them for treason for committing such an act of atrocity against such a prized bottle of liquor.

The room spun, the night air slipped through the windows, and they lay on the settee with the windows open and the crash of the waves as John combed through his impossible hair.

"Still say swimming."

"Mmm drowneded. Would druther John not drowneded," he'd had less than the other man but liquor did strange things to his system. His metabolism was not meant to break down such components, even in a human body.

"Hah! Don't think....youuuuu can even... even..." John tossed up an arm looking for the word.

"Swimming?"

"That."

Sherlock chuckled, "Like a God. Like... like... Poseidon" he said chuckling at his own wit.

John leaned forward burying his face in Sherlock's hair, "Can't remember the universe. Can remember Greek Mythology?"

Sherlock purred under the administrations, limbless and relaxed as he opened his eyes up at him, "Greek?"

"Poseidon?"

"Isn't greek. Mer." He said firmly shaking his head. He raised a hand brushing John's cheek, "Not part of humans...."

"Mmmm" John chuckled, "And what does that make....you God-like one?"

Sherlock was about to say Mer before the words slipped away. Drunk as he was it was too tightly held a secret, "Yours." He said instead. Because it was true, because he wasn't sure that when he went back to the water to change he wouldn't simply scatter into the foam on the tops of the water.

John's fingers stopped carding his hair. Sherlock feared for a moment he had offended him, but instead John's other arm wrapped around him tightening slightly. He thought he felt a ghost of lips across the top of his crown, and for a moment his blood rushed hot and fervent.

"John?" he said softly.

But the fingers had resumed their carding and he lay snugly in his arms as he drifted off into sleep.

* * *

 

_He tore out another page in the book and tossed it in the fireplace with a yell._

_John was away. John was constantly away now, so it would not be there to see._

_"Not so simple is it baby brother?"_

_He swerved and the book flew across the room, only deflected by Mycroft quickly raising his umbrella._

_"Get out."_

_"I think not," the other man took a seat across from him._

_Mycroft's lips pursed, "I warned you Sherlock. Love is a worse mistress than anything the sea might have for you-- Do you not see it is time to stop this madness before you lose all sensibility?"_

_"Love?" snarled back Sherlock. "You see as well as I that I have no soul."_

_"Ah but brother, it's never that simple now is it? Though do try to refrain from dramatics even if Doctor Watson has married-- I would hate to tell Mummy you've chosen sea foam over your family."_

_Another book flew across the the room._

* * *

 

  
The east wind slammed across the windows of the cottage as the rain pelted down relentlessly.

The hangover would have been bad enough, without the addition of the storm that continued without ceasing.

John awoke to feel Sherlock slip from his arms. They were still both partially clothed, in so much he still had his pants on, although he struggled to remember the exact details of later in the evening.

Sherlock was standing up, fully turned to the ocean with the door opened. His body seemed to glow in the lightening, and the wind whipped through and tugged at his hair. His eyes were wide as the rain battered at him, and his fist was white from the effort to keep himself there.

"Sherlock?"

John struggled to stand as the man took a step outside. He thought he might be sleep walking, except Sherlock's breathing was quick- fast, and there was an awareness in his eyes that said it was impossible.

"Leave....leave me be John," his hand grew tighter and the thunder rocked the small cottage.

The winds tore apart shingles.

Odd. The weather had suppose to be clear, "Bloody hell Sherlock! Shut the door before the whole place comes down about our ears."

No response. He could feel the wind touching him and the detective took a step out into the night. He held his breath and stood as Sherlock took another into the storm. The rain beat against his chest and Sherlock licked his lips as though tasting the water's qualities.

"Sherlock!"

"Let me go John!"

John grabbed for his arm to swing him around, stop him from going even as Sherlock's legs nearly gave was he ran forward. He was surprised to hear a curse fly from the other man's mouth as the storm grew wilder. John could barely stand in the wind, and couldn't fathom how Sherlock was managing.

There were voices on the wind, and he could feel the rain biting against him. Sherlock ran headlong towards the water as the wind and sand swirled about him.

The storm stopped John just shy of the beach. An invisible wall pressed against him as he heard Sherlock cry out the moment his feet touched the waves. His scream became caught in the gusts and they wrapped around John as he stood trapped in the sound.

It was enough to break him free. Enough to make him to fly across the sand and the wind and the crashing waves that threatened to take anything in their wake back with them out into the squall. He saw Sherlock slide down, taken, and the words were ripped from his throat.

"Sherlock! Damn you, no! Not now!"

All they'd been through? He would not let a moment's stupidity take his best friend.

As he slammed into the waters he found the waves subsiding. He continued to move and the thunder was gone and the clouds broke to give way to sunlight that blinded him as he pushed through the calming water.

There was a groan behind him and he swerved.

"Idiot!"

Sherlock lay across the beach, arms bent and shaking as he tried to sit up.

John froze when he saw the rest.

Yes it was Sherlock.

From waist to head it was truly Sherlock, even if there was a silver tint to his skin, and small slits along the sides of his throat that looked like gills.

At his waist came the change. Blue and silver scales starting at his navel and flaring along his hips. These slowly gave way, not to legs but rather a long iridescent fish tale. It glistened and gleamed in the light, blue and silver and infused with a glow that shone and sparkled in the sun. It was easily three times the length of his torso, and fanned out in a beautiful fin that glinted violet in the light. Fins and fans fluttered from the sides reminding him of that of a lionfish’s, they created flourishes too detailed to be anything but real.

Sherlock's head lifted and he caught sight of John's expression before lifting himself up off the ground and moving to dive into the shallows. A moment later John was across the shore grabbing his wrist even as Sherlock struggled against the hold. "Sherlock no!"

He tugged on his wrist trying to pull away but John dug his feet into the sand and kept his eyes carefully schooled on the Mer.

"No."

The tail thrashed, a piece of fin caught his leg and sliced through the fabric. John winced feeling it cut into his leg, but paid no attention as he kept his grip, "I want an explanation" he snapped angrily. "You are not diving off into the ocean so I never bloody well see you again."

"I-"

"The whole time? The whole time? You don't think it was pertinent to tell me? God, wasn't dying bad enough? But this!?"

Sherlock was looking out at the sea, "To your people I may as well be a monster John. Yes, I am well aware of what I did, but I assure you it was not entirely by choice. I was allotted a certain amount of time to spend on land and unfortunately the time is up. I had thought I would be able to delay the action, but it would seem to be more impossible task than I had surmised."

"Then the other night..."

"Was no dream. I am sorry for the subterfuge, however I believed you would take it poorly if you knew."

John stared at him in disbelief. The tail was still dipping in and out and his bit the side of his mouth to ensure he was awake. His voice was dry, "What? That Mermaids are real?"

"Merfolk. We hardly call ourselves that, but it is a suitable enough terminology in English."

John scowled, "What else then? Fairies? Unicorns? Next you'll tell me Mycroft is a vampire!" He paled looking angry, "Wait does that-"

"Of course he is. He however has a stay of action and remains on land more than with our kindred. Unfortunately my work does not seem important enough for such a stay of action, meaning I have no way to work around my ultimatum."

John's fist grew tight, his eyes narrowing as he looked on with an ever growing fury, "So what then? Were you just going to swim off? No goodbye? No final stories? Just disappear and leave me stuck here to lose you again? Dammit Sherlock!" He stared down at the tail shaking his head, "It's unbelievable but-"

"Yes unbelievable! If I had told you what proof would I have? You'd have never believed me, and if I joined you into the sea how should I think you might have acted? Impossible to tell. It's an absurd enough notion for any mortal, and you are not one to believe easily. I was hoping I might find a way to stay in which you never needed to know the truth."

John glared, "Is that possible?"

"I had thought so once."

John scowled, "So now you'll just give up?"

"The alternative is sea foam, and on a whole I believe I am partial to a corporal form at the moment, contrary to you and my brother’s undiminished belief I do not, in fact, have a death wish."

"Sherlock," he said resting in the sand next to him eyes taking in his silver body. His blue eyes were stormy, and reminded him of clouds at sea in their colour and denseness.

It was impossible to say how long they sat like that. Sherlock turned back to the sea, unable to face John but just as unable to leave. John letting his mind work around what he had just learned.

John broke the silence first, "May I?" He asked motioning to the tail.

Sherlock paused and then nodded, as John rested his hand and allowed it to glide along the scales. He felt a ripple move through the man and paused "Are you alright?"

"Sensitive. It.... It has been a long time," he murmured under his breath.

John let his hand run along the length again, watching the scales ripple and dorsal fins fan out under his fingers. His eyes flickered to where Sherlock had buried his fingers in the sand, head turned firmly away before John pulled back his hand.

"Where will you go now?"

Sherlock's eyes flickered over the water, and John could see just a hint of anger flash in his eyes. "Back to Atlantis I suppose."

The anger was replaced with laughter when Sherlock saw John's jaw fall at his words. "Really John? I've just proven Merfolk exist and you're more aghast at the idea Atlantis is a real place? There's far more contextual evidence leading to it's location then the silly tales of Mer that scatter throughout your lore."

"But-"

"Why even Aristotle did a fairly accurate mapping of the island when it was still above water. I hardly see why it's so difficult to believe. In the last century or so you have had at least one, nearly two major islands that were decimated by an earthquake. During the time of Atlantis we were more apt to meddle with mortals, and your kind more open to belief in us. Indeed, some cultures would leave offerings on the beach believing us to be gods and children of gods. We spent much time surrounding Atlantis and trading our knowledge with that of Mortals, and when the explosion occurred we rebuilt what we could of it in our waters."

"It's a bit much to take in."

"I still see how it's less shocking than my heritage," he said letting his tail flop in the sand.

John's eyes flickered back and then looked out to the sea, "It's... shocking. I can't deny that, but then you've always surprised me. I guess... I suspected at times that there was something else. Frankly, I think you could've sprouted wings and announced you were an angel and I wouldn't have bat an eye."

Sherlock's lips curled, "What? Not hell-spawn?"

John grinned, "I think we'll save that revelation for Moriarty."

They both laughed, giggling on the beach like school boys for all the inappropriateness. John recovered first and lay back on the sand, reaching next to him to grab Sherlock's hand. He hesitated for a moment, feeling the webbing and slight ring of scales that met at the wrist, but a moment later he wrapped his fingers with Sherlock's and let out a long breath.

"Sherlock. Please tell me there's a way around this, I can't lose you again."

The detective was silent, "...perhaps. Perhaps after I've spent sometime back at sea I will be allowed back. You know now so you could visit of course and I-" His calm rationing quickly dissolved into babble. His own hand tightening on John's, even knowing he'd have to slip into the water soon or risk his skin drying out.

John rolled over, propping himself up on elbow and reaching out with his other hand to cup Sherlock's cheek, "Blood hell, you don't make it easy do you?" he asked running his hand along his cheek.

Sherlock's mouth went dry, "John?"

John laughed leaning forward, "Don't you know?"

Sherlock felt a chill run up his spine and John stopped just a hair's breadth from his lips, "To love you."

He surged forward.

The spark was immediate, a thrill of heat that pushed through them both. The kiss was tentative at first, but John refused to let him go and Sherlock let himself pulled closer. His free arm fell to his side, and his hands were still entangled with the other man's. He felt John's tongue slip between and he opened his mouth to allow him entrance trying to taste, touch, feel every moment of the action.

Why oh why did it have to be now.

"Well isn't this sweet" said the dry voice somewhere behind them. John and Sherlock sprung apart although their hands were interlocked. "A shame too late- "

Mycroft stepped out onto the shore with his umbrella in hand and careful to stay away from the damper area of sand. Sherlock scowled and shifted enough to slam his tail in a pool of water attempting to send it towards the man.

It fell short.

"My, my, such a childish action. I would so hate to ruin the suit Sherlock," he said, raising his eyebrows and raising his eyebrows sharply.

"How are you even here?" snapped John. "You could undo this couldn't you? Do you hate Sherlock that much?"

"John," murmured Sherlock reaching for his wrist as the other man situated himself between the two brothers.

"Wrong."

Mycroft tapped his umbrella against the sand, "The dispensation I enjoy extends only to me. I assisted in the initial change, and yes had the power to revoke- but the seven year stipulation is something far beyond anything in my doing. The sea has claimed her own, and I am afraid I am unable to undo the action." He sighed looking past his brother for a moment, "As to why I am here, I planned to come to console my brother once the change occurred. I knew of course his time was up and suspected something like this may occur. When the storm came up I knew it was time. I had not expected your presence," he said glaring at John.

John glared back, "There's something else."

"John stop. Let it go. I have checked, there's nothing you can-"

"You're not leaving me again!" he shouted before swerving to pin Sherlock in the sand.

Sherlock's pupils were blown and he closed his eyes to turn away his head. He laughed as he felt dampness on his cheeks but no change in his physicality. A pain shot through him, his heart raced, but still nothing.

Mycroft sighed, "A soul. You may be the first brother. A Mer with a soul to call his own. Mortality trapped in the skin of our people, at least for seven years...."

John pushed back in horror as Sherlock slipped out of his hold turning away to hide his face.

"Sherlock?" He whispered.

The roar of the waves filled the silence.

"Fine," the doctor turned back and rose to look at Mycroft. "Fine then. How do I... change?" He said clearing his throat and looking at the man.

It apparently caught Mycroft off guard, "What?"

"Seven to sea, seven to land-- that was his agreement. If he could become mortal then there must be a way I can become Mer. If he's to go back to his kingdom for seven years then I'll go with him. You'll come up with our excuses I have no doubt- and while I'm not pleased at disappearing on Mrs. Hudson like that I'll take that over going back without him." He crossed his arms, "Go on then."

Mycroft's lips pursed and Sherlock had turned back, eyes wide and hopeful, a thought on his face as he looked at John, "He's right." He told Mycroft "It should work two ways. There is history implying-"

"Yes Sherlock I am aware," he paused glancing between them. "I will need to gather the proper things, no it is not as easy as it was with your legs Sherlock, given he is not inherently Mer. It may not work at all-" his eyes flickered over John. "Doctor Watson, return and settle your life in order- if at the end of the week you decide this is still your choice I will meet you at the London Docks at midnight and we can discuss the matter further. Agreed?"

John paused before nodding, "I won't. Change my mind that is. But yes-" it was fair. He knew what he was losing, what he might still lose but, "Agreed."

"A week," Mycroft nodded to them both and turned heel to go before adding, "And I dare say you had best truly love my brother. Without that no strength of spell will assist you."

* * *

 

_"It's strange," said the other Mer. "You're always going on about growing legs, and yet a few of ours have gone off like Mycroft.... but I have to wonder. Humans are half Mer aren't they? Technically. Why aren't there any tales about them joining us?"_

_Sherlock turned from his revery to stare at Victor in surprise, "Why would they?"_

_Victor hummed, "Same reason you want to go on land I should think. Adventure, exploring, I know you're bored with our day to day life, but there's whole other lands to see under the water. Places off limits that have to hold secrets even our people are unaware of."_

_Sherlock's eyes followed a speck on the horizon and frowned, "It is a thought."_

_"Might help you find a way to get those legs you keep yammering about," Victor smiled at him._

_Sherlock frowned, "Might. Doubtful. Whatever a mortal would do to become a Mer would likely entail a separate set of rules from our bylaws. Hardly matters when I'd rather not return at all once I'm back on land."_

_Victor shrugged and slid back into the water, "Something to think about Sherlock."_

_"I'm going on land to escape boredom Victor, not to befriend some mortal. Whatever it would take, somehow I don't think it shall matter."_

_Victor laughed, "Ah Sherlock, but when have you ever been allowed anything to be that predictable?"_

__

* * *

 

Moonlight floated over the London Docks a week later, the boats silent and adrift, and not another human to see the figure that pulled off his clothes and leaned to the side.

In the water two arms lifted up, glistening with a faint hint of scales, and catching the man as he slipped into the chilled water.

A laugh erupted, deep and rich as the moonlight wrapped her rays around the two of them and the water shone bright with starlight.

There was a splash, a hint of red and gold that glinted under night sky before it disappeared into the depths, intertwining with blue.

 

**Author's Note:**

> Much of where I got the idea came from Oscar Wilde's "Fairy Tale" "The Fisherman and his Soul." It involves a man who falls in love with a mermaid and wishes to become one of them. The only way to become one is to give up his soul, and he has to find a way of doing so to join her. It's a fairly dark tale that's an interesting take on the mermaid legend. I highly recommend reading it (it's also a direct contrast to the Little Mermaid that was it's contemporary).


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